Tom Hanks proved that the highlight of being shipwrecked on a deserted island is being able to lose an intellectual argument with a volleyball and throw it away in disgust.
Sometimes, in life, you wish you atleast had that volleyball. Loneliness isnt just about not having anybody around but not being able to associate yourself with those around you. I think the following cartoon strip highlights a certain feeling of unwantedness which precedes loneliness. Its probably not sad in the existential sense, but I wanted to set the context. (Link)